Acanthamoeba Keratitis

Acanthamoeba Keratitis is a painful eye condition that, although rare among contact lens wearers, can have serious complications for sufferers. The condition can result in visual impairments or permanent loss of sight. In some severe cases, a corneal transplant (surgical procedure) is needed.

Acanthamoeba Keratitis is difficult to diagnose and difficult to treat, however by following a careful hygiene routine when inserting and removing lenses you can significantly reduce the risk of contracting this infection.

The first diagnosis for the condition was in 1973. And since then, roughly 90 percent of cases have involved contact lens wearers. This is because the infection can sit comfortably and fester between the lens and the eye.

What are Acanthamoeba?

Acanthamoeba amoeba are naturally occurring, one-celled organisms and are commonly found in sources such as tap water, sewer systems, saunas, hot tubs and pools. When amoeba infects the eye, this results in Acanthamoeba Keratitis.

What causes Acanthamoeba Keratitis and what are the symptoms?

Acanthamoeba Keratitis is caused by contaminated water coming into contact with the eye, and an infection can happen while wearing contacts in the shower, while swimming or when using non-medical approved contact lens solutions or tap water to store lenses.

Acanthamoeba Keratitis can be difficult to initially detect as the symptoms are very similar to other common eye infections. Some of these symptoms include redness in the eye, increased sensitivity to light, eye pain, blurry vison and the constant feeling of something in the eye, while infected eyes can often display a white ring around the iris and severe redness. A ring-shaped ulcer can also appear in later phases of the infection.

Preventing Acanthamoeba Keratitis

Despite the consequences if contracted, the infection is incredibly easy to prevent as long as you practice good hygiene whilst wearing contact lenses. We suggest reading our page on how to correctly insert and remove your contact lenses.

In summary, here are the main actions you can take to avoid infection:

  • Wash your hands thoroughly before handling contact lenses
  • Don’t use cleaning or storing solutions that aren’t specifically designed for these purposes. Also note the different purposes for different solutions. Saline, for example, is not appropriate for disinfecting, and can only be used for wetting and short-term storing
  • Use fresh solution each time you clean your lenses and contact lens case
  • Don’t sleep in lenses that are not designed for long term use
  • Don’t wet contact lenses with water or saliva
  • Never use lenses that were worn by someone else
  • Gently rub and rinse contact lenses before inserting and after removing them, before putting them back into their case
  • Replace your lens case every three months

Treating Acanthamoeba Keratitis

Medical treatments for Acanthamoeba Keratitis are not fully established, and are mostly done by trial and error depending on what the patient responds too. This is why early diagnosis is incredibly important.

One method is a high dosage of topical antimicrobial agents. These are concentrated on the area of the infection site. Cysts can become highly resistant to therapy, so a strong combination of substances are used.

A recommended combination may include; chlorohexidine (0.02%) and polyhexamethylene biguanide (PHMB, 0.02%) for treating both the trophozoites and cysts. Using one of these agents in combination with propamidine (Brolene) or hexamidine (Desmodine) may also be suggested.

Quick links:


Can I swim with contact lenses?
Can I clean my contact lenses in water?
A guide to eye infections